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RD8000 Generator Load Meter

02-11-2010, 09:59 PM

Just got this portable generator today and got it up and running. As a simple first test under load I plugged in a 120V 1500 watt space heater. The load meter on the RD8000 display panel read 40% !!!!. Surely this isn't right for a unit rated at 8000 watts. Any advice much appreciated.

Well a second review of the manual may, at least in a ballpark way, explain the load indication I observed. The manual states that the load indicator only monitors 4800 watts of the total 8000 watt output. 1500 would be 31% of 4800. Not right on the money but a lot closer to what I observed. Wonder why the load indicator doesn't measure against the total 8000 watt capability? Oh well, its conservative if nothing else

Comment

First I do not have one of these generators, but most likely it is only reading the 120 volt load, on 1/2 of the generator,

the 8000 watt capacity is on 240, or 4000 on each 120 volt circuit,

the way a small generator is set up, there is a 240 volt generator, that is cut in halve to provide the 120 volt circuits,

the generator (alternator in reality), is rated on it maximum capacity, at 240 volts,

And it would not surprise me any if the ratings are some what exaggerated a little or a lot,

each circuit (120 volts), is most likely over load protected, but the most one would want to Load on each side is a max of 4000 watts, your unit and the items your running will benefit if you only load about 2/3 of that, most likely it is only rated for about 70% to 80% of that on a continuous load, If it is pure Resistance load there may not be the need for backing off much, but if any motor loads are attached to the generator, I would not load it to more than about 60% of the run loads, and the reason is a motor many times can need double of the run amps to start the motor, (I am guessing you have seen lights dim when some motor starts), that is caused by the starting amps,

when your operating off the grid, (power company), it is like having a huge tractor pulling the load, when you hook up the generator, you have now hooked up your lawn tractor to the loads, and when it kicks in the load is noticed, and if the load is extensive it will lug down the unit even to the point of stalling the unit out,

(years ago the farm had a power outage, 30 days, my mother wanted to wash some clothes, so we pumped up the water, and set the generator to the washing machine and this unit had a special switch to tie the two sides of the 120 volts together so one could get the full 3750 watts from the unit on one 120 circuit, so we set it up that way, and she turn on the washer, the motor kick in and the it killed the generator dead, the motor on the washer machine pulled so much power it literaly killed the unit, and other motor loads would really make it lug, (the problem is when it starts to lug down is you have a change in cycles, which make it harder for the motor to work, and thus it pulls more amps, and usually the voltage drops as well, causing the motor to pull even more amps, thus your over heading the motors (potently damaging other sensitive electronics in the process) and causing some major heating and control problems in the generator it self.

but to not expect the same output from the generator, as the grid,

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Comment

try plugging it in to the other outlet, and see if that changes any thing,

like I said I do not have one and have not looked at the manual or schematic to see how it is wired, but my guess is it is only metering one side,

when ever using a portable generator on 120 loads try to put about the same watt load on both of the outlets, if your using more than one load.

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

I tried to find the manual for this generator on the RIDGID web site but so far can't find it. I did download the parts list and hope there is a wiring diagram. Maybe someone can link me to the manual download.

With the meter showing a 40% load with one heater connected, this would be pretty correct as 1500 is 37.5% of 4000 and with the heater being 120 Volt it is connected to one half of the generator. The generator may be 2 windings series connected so as to have 120 + 120 Volts and 4000 Watts rated power output per winding, or it might be one winding with a center tap for neutral. In either case you can only draw 1/2 power for any given 120 Volt load / receptacle. What would be interesting is to try running a second heater of the same kind, but plugged into another receptacle. Then for just a few seconds try both heaters in the same receptacle.

The load meter could be setup for only one side connection or it might be able to sense 120 Volt or 240 Volt loads and give readings accordingly.

I really need to see the circuit diagram or have a generator of this model here for some testing.

I think BHD's posts have the correct idea.

Sometime if I can find them, I'll try to post graphics showing generator windings and connections.

Comment

Quick update: Please try plugging the heater into a different receptacle and note the load meter readings.

To the member that has a 0 reading, please try plugging just one good load such as a portable heater or toaster into one of the 120 Volt receptacles and then into another receptacle while watching the load meter.

I hate how some generators are setup with regard to Volt and Ammeter connections. There really should be a 0 - 300 VAC Volt meter and TWO (not just one) Ammeters where each hot lead would have its own Ammeter. In the instructions there would be a section about load balancing. I also hate that in too many cases they have receptacle protection and skip the super important main breaker or main fuses to protect the generator itself.

Comment

But i have it plugged into the far right that saws 120v/240v and then back fed into Breaker panel have fridge in house and a deep freezer a few lights tv the gauge saws ZERO amps cant be right...............I got a lemon ..........

Comment

I down loaded the parts PDF, http://www.ridgid.com/ASSETS/95FA20D...000-%20RPL.pdf
on page 6 and 7 it appears that the power meter is on the removable box, and it should be able to read (it appears to me amps or guessing percentage of the generators capacity from either side of the 120 load or 240 volt, now I do not know if it only reads the higher of either side of the 240 (which is my guess) as if your pulling 4000 watts of power off of one 120 volt plug, then that 1/2 of the generator is at capacity, and it may read 100%, even tho your only pulling 1/2 of the generators total capacity, as it is the total capacity of that half, but to add more to that side would over load the generator but one could still get additional off the other side. ( am not sure with more documentation or playing with one to know exactly how the meter works but it appears to read the amps from both sides, and the voltage from one side, but that is not unusual, as many times the voltage regulator only reads one winding,),

OK that is on the removable box, and it looks as if the power needs to be pulled from the box for the meter to read it, if your plug in to the generator at the 240/120 volt twist lock it appears to by pass the meter, there is set of breakers for the box and one for the twist lock receptacle,

or that is what it appears to me, I would think the manual would give some explanation, but it does not seem to be a down loadable manual for either the 8000 or the 6800

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

Thanks understand now. No % of load or Graff /////////// indication just get to see how many hours Ive put on the generator...Well the power is back on put 20 hours on the thing time for oil change and store it for next storm it worked as advertised. Thanks for your info on load meter.

Comment

If your going into long or potential long term storage, I would suggest to drain out the fuel and then run the unit until it runs out of gas, if your in a humid area, sealing off the exhaust and the intake (air cleaner) may be a good idea, or using some fogging oil, if your going to store your fuel I would suggest "Sta bil" or "PRI-G" as an additive,

IMO it is actually good for the generator if it is "exercised" on a quarterly basis, (first your fuel is keep basically fresh, and second there is the possibility of the generator losing it residual magnetism, (I have never had it happen but most manuals will give some procedure on how to flash the coil to restore it), with out the residual magnetism it can not start to generator power, also if some thing goes wrong with it, (mice or some things else) you will know to get it repaired before your in an emergency situation.

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

Purchased 3- 8000 watt units for a construction job ran units solid 8 hr a day for 2 months. No Problems startes every day ran full day on a tank of gas. solid unit plenty of power.

The problem i did have is the rims snapped at where the ball bearings sleave meets the rim . I had this happen on two out of the 3 units, they break very clean from the rim and can be welded . has any body else had this problem.